How to sell or license a patent
You can sell a patent outright (an assignment: the buyer becomes the owner) or keep it and license it (others pay to use it). Either way: check the patent is in force and fees are paid, put a value on it, find companies that use or need the invention, agree terms in a written contract, and have the change recorded in the patent register, at the EPO for a pending European application and at the national office, such as DZIV in Croatia, for granted patents.
Sale or licence: what is the difference?
In a sale (an assignment), ownership moves to the buyer. You are paid once, or in instalments, and the buyer takes over the patent, including paying its renewal fees and deciding whether to enforce it.
In a licence, you stay the owner and give someone permission to use the invention on agreed terms, usually for a royalty on their sales, a fixed fee, or both. A licence can be:
- exclusive: only the licensee may use it (often even the owner gives up using it),
- non-exclusive: you can license several companies,
- limited to a field (for example medical devices only), a territory (for example Croatia and Slovenia) or a period.
A sale gives certainty and money now. A licence can earn more over time, but you keep the costs of owning the patent and depend on the licensee's sales.
Step 1: know exactly what you own
Before any conversation, check the facts a buyer will check:
- Status: is it granted, or still an application? Is it in force in each country you plan to offer?
- Renewal fees: unpaid fees end a patent. In Croatia, annual fees are due from the third year after filing (Zakon o patentu, Art. 88).
- Remaining term: a patent lasts 20 years from filing; buyers pay less as expiry gets closer.
- Countries: protection only exists where the patent is in force.
- Ownership: the register should show you as owner, with every earlier transfer recorded.
Step 2: put a rough value on it
There is no list price for patents. Two simple views help you prepare:
- Cost view: what it took to obtain and keep the patent (filing, grant, validation and renewal fees). It is a floor for many sellers, not a market price.
- Income view: what a licence could earn. Take the yearly sales of products that use the invention, the share of their value that comes from it and a royalty rate, and add it up over the years of protection left. One published study of licence agreements disclosed in US company filings (1984–2007) found median royalty rates of 3% in chemicals, 4% in medical devices and 4.4% in pharmaceuticals. These are historical, illustrative figures, many of those licences also covered know-how, and real rates vary widely.
Real prices depend on who the buyer is and what they need the patent for, so treat any figure as a starting point for negotiation.
Free toolPatent Valuation CalculatorBoth views, from a patent number and your own figures.Try it →Step 3: find the right buyers or licensees
The best candidates are companies that already make or plan to make products using the invention, followed by their competitors and suppliers. Ask yourself:
- Who sells products in this field in the countries where the patent is in force?
- Who would be blocked by the patent if they entered those markets?
- Who cited this patent or filed similar patents? A patent search shows them.
Prepare a one-page summary: what the invention does, the patent number and countries, status and remaining term, and what you are offering (sale, exclusive or non-exclusive licence).
Free toolAdria Patent SearchFind companies with patents close to yours.Try it → Free toolAdria Patent MarketList a European patent for sale, licence or co-development.Try it →Step 4: agree the terms in writing
Sale and licence agreements are legal documents. Have them prepared or reviewed by a lawyer. The points that usually decide their value:
- Price or royalty: the rate, and above all the base it applies to (net sales of what exactly?), minimum payments and reporting.
- Scope: exclusive or not, field, territory, duration.
- Who pays renewal fees and who decides about enforcing the patent.
- Improvements: who owns later developments.
- Warranties: what the seller promises about ownership and validity.
Step 5: record the change in the patent register
Transfers and licences are recorded in the patent registers. The Croatian Patent Act lists transfers of rights and licences among the entries in the register kept by DZIV (Art. 21 and 22). Where to record depends on the stage:
- Pending European application: the EPO records the transfer in the European Patent Register, on request with a document proving the transfer, and a fee.
- Granted European patent: during the nine-month opposition period, or while opposition proceedings are pending, the EPO still records transfers. After that, they are recorded with the national office of each country where the patent is in force, in Croatia with DZIV.
- Croatian patent or utility model: with DZIV.
Until the change is recorded, the register still shows the previous owner, and that is what the next buyer or licensee will see.
Frequently asked questions
Can I sell a patent application before it is granted?
Yes. Applications can be transferred, and for a European application the EPO records the transfer in the European Patent Register. Buyers usually pay less, because the application may never be granted, or granted with narrower claims.
Is it better to sell or to license?
It depends on what you need. A sale gives money now and ends your costs and responsibilities. A licence keeps the patent yours and can earn more over time, but your income depends on the licensee’s sales and you keep paying the renewal fees unless the contract says otherwise.
What royalty rate is normal?
There is no single normal rate. One study of licence agreements disclosed in US company filings (1984–2007) found median rates of 3% in chemicals, 4% in medical devices and 4.4% in pharmaceuticals, but those are historical figures and individual deals vary widely with the product’s margin, exclusivity and how central the patent is.
Who pays the renewal fees after a sale?
After a sale the new owner normally pays them, as the patent is theirs. In a licence the owner usually keeps paying, unless the agreement shifts the cost to the licensee. Write it into the contract either way.
Do I need to record the sale anywhere?
You should. Transfers and licences are recorded in the patent register: at the EPO while a European application is pending (and during the opposition period after grant), and at the national office, such as DZIV in Croatia, after that. Buyers check the register to confirm who owns the patent.
Sources
- Zakon o patentu (Croatian Patent Act), Narodne novine 16/2020
- EPO Guidelines, Part E, Chapter XIV: registering transfers, licences and other rights
- EPO Guidelines, Part E, Chapter XIV, 4: transfers during and after the opposition period
- Porter, Mills & Weinstein, “Industry Norms and Reasonable Royalty Rate Determination”, les Nouvelles, 2008
Checked on 12 October 2026 against the Croatian Patent Act (Zakon o patentu, NN 16/2020) and the European and EU rules listed in the sources. This guide gives general information, not legal advice, and rules and fees change: check the official sources, or talk to us about your situation.